1. Field of the Invention
This invention relates to a printer head, and more particularly to a write head for an optical printer utilizing the principle of a fluorescent display device.
2. Description of the Related Art
Optical printers utilizing various kinds of write heads have been proposed. The optical printer is generally constructed in such a manner as shown in FIG. 8. The optical printer shown in FIG. 8 includes a photosensitive drum A which acts as a record medium and is rotated about an axis 0 in the clockwise direction as shown in FIG. 8 so that its surface may be charged by an electrifier B. The surface of the photosensitive drum A is irradiated by dot-like light from a write head C to form a latent image of letters, figures or the like thereon. The latent image is then developed by a developing device D. Decalcomania papers F contained in a cassette E is fed between the surface of the photosensitive drum A and a transfer device G so as to transfer characters, figures or the like formed on the photosensitive drum A to the decalcomania paper F. The image transferred to the paper F is fixed on the paper by passing it through a thermal fixing device I. In FIG. 8, reference numeral H designates an erasing lamp for erasing charges remaining on the photosensitive drum A and J is a cleaning blade for cleaning the surface of the drum A.
Conventionally, an LED (light emitting diode), a CRT (cathode ray tube) or the like has been used as a write head C for such an optical printer. Also, an optical printer head has been recently developed which uses the principle of a vacuum fluorescent display device in addition to the light emission devices such as LED and the like in view of the reliability and the manufacturing costs.
The vacuum fluorescent display device is a kind of a multi-electrode electron tube which includes a casing evacuated to a high vacuum in which various electrodes and phosphor layers are contained.
Now, the conventional printer head using the vacuum fluorescent tube (hereinafter referred to as fluorescent printer bead) will be described.
The fluorescent printer head is classified into two types according to the direction of light emission, namely a VFD (vacuum fluorescent display) type and an FLVFD type (front luminous vacuum fluorescent display).